help sick beardie

hi, new to having a beardie, got him in march, he settled inb really well, they told me he,s about 18months, he,s in a 4ft x2ftx2 ft viv, but middle of april found he had mites, so treated him as vet recommended, with front line spray, he was on bark chippings but got rid as was told thats where the mites prob came from, but its been about 1 month since i started treating him for mites and he,s on paper now, but he,s gone very lazy, hardly eats maybe 1 locust in 3/4 days, hasnt poo,d for week so bathed him, this is the 2nd/3rd week he been like this, he did poo in bath really smelly and part of poo is like alittle sack, only way to describe it a cream little sack and this is the 2nd time i,ve seen this in his poo, please help, i,m very worried,